Using the binary_tree_node, write a function to meet the following specification. Check as much of the precondition as possible. No recursion is needed. template
void subswap(binary_tree_node* root_ptr)
// Precondition: root_ptr is the root pointer of a non-empty binary tree.
// Postcondition: The tree is now the mirror image of its original value.
// Example original tree: Example new tree:
// 1 1
// / \ / \
// 2 3 3 2
// / \ / \
// 4 5 5 4